Insights into the role of deep-sea squids of the genus Histioteuthis (Histioteuthidae) in the life cycle of ascaridoid parasites in the Central Mediterranean Sea waters

Abstract

Ascaridoid nematodes comprise a wide range of heteroxenous parasites infecting top fish predators and marine mammals as definitive hosts, with crustaceans, squids, and fishes acting as intermediate/paratenic hosts. Limited data exist on the species and role of several intermediate and paratenic hosts in the life cycle of these parasites. In the aim of adding knowledge on the role of squid species in their life cycle, we have here investigated the larval ascaridoid nematodes collected from the deep-sea umbrella squid Histioteuthis bonnelli and the reverse jewel squid Histioteuthis reversa captured in the Central Mediterranean Sea (Tyrrhenian Sea). Morphological study and sequence analysis of the internal transcribed spacer (ITS) regions of the ribosomal DNA (rDNA) and the mitochondrial cytochrome c oxidase subunit 2 (mtDNA cox2) gene locus revealed the occurrence of Anisakis physeteris and of an unidentified species of the genus Lappetascaris. Sequence analysis revealed that specimens of Lappetascaris from both squid species matched at 100% sequences previously deposited in GenBank from larval ascaridoids collected in octopuses of the genus Eledone of the Mediterranean Sea. The Bayesian inference tree topology obtained from the analysis of the fragments amplified showed that Lappetascaris specimens were included in a major clade comprising Hysterothylacium species collected in fishes of the families Xiphiidae and Istiophoridae. As regards the site of infection in the squid host species, A. physeteris larvae predominated (60.7%) in the gonads, while those of Lappetascaris (76.3%) were found infecting the mantle musculature. The overall high values of parasitic load suggest both squid species as transmitting hosts of third stage larvae of Lappetascaris to top predator fishes, as well as the umbrella squid as an intermediate/paratenic host in the life cycle of A. physeteris in the Mediterranean Sea.

A molecular and ecological study of Grillotia (Cestoda: Trypanorhyncha) larval infection in small to mid‐sized benthonic sharks in the Gulf of Naples, Mediterranean Sea

“…Sharks used in the present study constituted the bycatch of scientific and commercial trawling operations (red shrimps’ and pink shrimps’ fishery activities) held with a commercial fishing vessel equipped with bottom trawl nets (mouth of 3 × 4 m in height and width, respectively; 40 mm mesh size), towed at ~2–2.5 kn on muddy bottoms (Crocetta et al., 2020 ; Palomba et al., 2021 ). Samplings were performed in accordance with the permit n. 0008453 (issued May 15, 2020) by the Italian Ministry of Agricultural, Food and Forestry Policies, the guide for the care and use of animals by the Italian Ministry of Health and the ARRIVE guidelines.…”

Proteomic Profiling and In Silico Characterization of the Secretome of Anisakis simplex Sensu Stricto L3 Larvae

“…This roundworm has an indirect lifecycle involving several hosts. Marine mammals are definitive hosts, fish, and cephalopods are intermediate or paratenic hosts, while crustaceans are intermediate hosts [1,2]. Humans, which are accidental hosts of A. simplex, are infected by third-stage (L3) larvae of this nematode, the source of which are infected marine fish or cephalopods [1,3].…”

Ascaridoid nematodes infecting commercially important marine fish and squid species from Bangladesh waters in the Bay of Bengal

“…Recently, Lappetascaris sp. Type A larvae was reported from the muscle and other tissues of the squids Histioteuthis reversa and Histioteuthis bonnellii from Mediterranean Sea ( Culurgioni et al, 2010 ; Palomba et al, 2021 ). The ITS sequence of Lappetascaris sp.…”

“…or Hysterothylacium sp., and deposited in GenBank as Hysterothylacium sp. (accession numbers MT365529 to MT365537) ( Guardone et al, 2020 ; Palomba et al, 2021 ). According to phylogenetic studies of the ITS region and cox2 gene locus, Lappetascaris sp.…”